1. Field of the Invention
The present invention is related to a serially connected double-phase full-wave brushless dc motor. More particularly, the present invention is related to two sensor/drive members used to control a serially connected type of the double-phase full-wave brushless dc motor.
2. Description of the Related Art
Referring initially to FIG. 1, it illustrates a schematic circuitry of a conventional single-phase full-wave brushless dc motor. The single-phase full-wave brushless dc motor in accordance with the prior art has a drive circuit 10 for driving a single-phase full-wave coil assembly. The drive circuit 10 includes a drive member 11, a sensor member 12 and a motor coil 13. The drive member 11 is electrically connected to the sensor member 12 and the motor coil, thereby Hall sensors detected by the sensor member 12 controlling current directions of the motor coil 13. In two-way directions, the excited motor coil 13 is capable of rotating a motor rotor by full-wave manner.
However, the rated power and voltage characteristic of the drive member 11 is changed nonlinear with respect to its dimensions. In other words, if the rated power of the drive member 11 is doubled, the dimensions have an increase of more than double. Thus, the increase of the rated power of the drive member 11 must result in an extra-occupation in an inner space of the motor.
Moreover, a large rated power of the drive member 11 must result in an increase of manufacturing cost. That is, the manufacturing cost of a double rated power of the drive member 11 must be more expensive than that of two regular rated power of the drive member 11.
In order to save the inner space and to reduce manufacturing cost of the motor, an additional drive member is added into the motor. Consequently, the motor accomplishes a double increase in rated power and a reduction in manufacturing cost. Meanwhile, the single-phase full-wave motor coil is divided into a pair of double-phase full-wave motor coils which are suitable for two drive members. In manufacture, the total dimensions of the two double-phase full-wave motor coils are substantially identical with that of the single-phase full-wave motor coil so that the entire dimensions of the motor coil may not be increased and the loop count of the motor coil may not be reduced.
The present invention intends to provide a double-phase full-wave brushless dc motor having two drive members for controlling a serially connected type of a double-phase full-wave coil assembly, each of the drive members provided with a small rated power. The serially connected type of the double-phase full-wave coil assembly substitutes a single-phase full-wave motor coil. Due to the small dimensions and the low manufacturing cost, the small rated power of the drive members substitute for a large rated power of the drive member that may enhance the rated power, minimize the dimensions and reduce the manufacturing cost. In manufacture, maximum number of the drive members of the motor is equal to or less than number of poles according to design choice.